2020-08-07
If you don't have three cards in hand when instructed to discard three cards, you discard your hand.
2020-08-07
Use the sacrificed creature's power as it last existed on the battlefield to determine how many cards you draw.
2020-08-07
You draw and discard cards all while Greater Good's ability is resolving. Nothing can happen between the two, and no player may choose to take actions.